Sparsity of Population Activity in the Hippocampus Is Task-Invariant Across the Trisynaptic Circuit and Dorsoventral Axis.

Evidence from neurophysiological and genetic studies demonstrates that activity sparsity-the proportion of neurons that are active at a given time in a population-systematically varies across the canonical trisynaptic circuit of the hippocampus. Recent work has also shown that sparsity varies across the hippocampal dorsoventral (long) axis, wherein activity is sparser in ventral than dorsal regions. While the hippocampus has a critical role in long-term memory (LTM), whether sparsity across the trisynaptic circuit and hippocampal long axis is task-dependent or invariant remains unknown.

Anterograde versus Retrograde Effects of Damage to Identified Learning and Memory Systems during Acquisition, Retention, and Re-Acquisition of an Instrumental Visual Discrimination Task: Dorsal Striatum, Perirhinal Cortex, and Hippocampus.

Background: The goal of these experiments was to determine which learning and memory system(s) were necessary for the retention of visual discriminations and subsequent acquisition of a second problem. The dorsal striatum should be involved in the acquisition and expression of this task based on previous work implicating this region in instrumental learning and memory processes. The perirhinal cortex has been implicated in learning and memory processes associated with visual information like objects, and pictures and may also play a role in the acquisition and/or retention of visual discriminations.

Repeated multi-domain cognitive training prevents cognitive decline, anxiety and amyloid pathology found in a mouse model of Alzheimer disease.

Education, occupation, and an active lifestyle, comprising enhanced social, physical, and mental components are associated with improved cognitive functions in aged people and may delay the progression of various neurodegenerative diseases including Alzheimer's disease. To investigate this protective effect, 3-month-old APP mice were exposed to repeated single- or multi-domain cognitive training. Cognitive training was given at the age of 3, 6, & 9 months.

Peripherally-administered amphetamine induces plasticity in medial prefrontal cortex and nucleus accumbens in rats with amygdala lesions: implications for neural models of memory modulation.

The amygdala has been implicated in a variety of functions linked to emotions. One popular view is that the amygdala modulates consolidation in other brain systems thought to be mainly involved in learning and memory processes. This series of experiments represents a further exploration into the role of the amygdala in memory modulation and consolidation.

Effects of maternal social isolation on adult rodent offspring cognition.

Prenatal experiences can influence offspring physiology and behaviour through the lifespan. Various forms of prenatal stress impair adult learning and memory function and can lead to increased occurrence of anxiety and depression. Clinical work suggests that prenatal stress and maternal depression lead to similar outcomes in children and adolescents, however the long-term effects of maternal depression are less established, particularly in well controlled animal models.

Independent effects of sex and stress on fructose-induced salt-sensitive hypertension.

Proximal tubule fructose metabolism is key to fructose-induced hypertension, but the roles of sex and stress are unclear. We hypothesized that females are resistant to the salt-sensitive hypertension caused by low amounts of dietary fructose compared to males and that the magnitude of the increase in blood pressure (BP) depends, in part, on amplification of the stress response of renal sympathetic nerves. We measured systolic BP (SBP) in rats fed high salt with either no sugar (HS), 20% glucose (GHS) or 20% fructose (FHS) in the drinking water for 7-8 days.

Mechanisms of decreased tubular flow-induced nitric oxide in Dahl salt-sensitive rat thick ascending limbs.

Dahl salt-sensitive (SS) rat kidneys produce less nitric oxide (NO) than those of salt-resistant (SR) rats. Thick ascending limb (TAL) NO synthase 3 (NOS3) is a major source of renal NO, and luminal flow enhances its activity. We hypothesized that flow-induced NO is reduced in TALs from SS rats primarily due to NOS uncoupling and diminished NOS3 expression rather than scavenging.

An assessment of the functional effects of amphetamine-induced dendritic changes in the nucleus accumbens, medial prefrontal cortex, and hippocampus on different types of learning and memory function.

The present experiments investigated the effects of repeated amphetamine exposure on neural networks mediating different forms of learning and memory. Different components of these networks were assessed using various functional assays. The hypothesis was that abnormal dendritic changes in nucleus accumbens, medial prefrontal cortex, and hippocampus mediated by repeated amphetamine exposure would produce impairments on forms of learning and memory dependent on neural circuits relying on these brain systems, and have little or no effect on other forms of learning not dependent on these networks.

Dietary fructose enhances angiotensin II-stimulated Na transport via activation of PKC-α in renal proximal tubules.

Angiotensin II (ANG II) stimulates proximal nephron transport via activation of classical protein kinase C (PKC) isoforms. Acute fructose treatment stimulates PKC and dietary fructose enhances ANG II's ability to stimulate Na transport, but the mechanisms are unclear. We hypothesized that dietary fructose enhances ANG II's ability to stimulate renal proximal tubule Na reabsorption by augmenting PKC-α activation and increases in intracellular Ca.

Stretch-Induced Increases in Intracellular Ca Stimulate Thick Ascending Limb O Production and Are Enhanced in Dahl Salt-Sensitive Rats.

Mechanical stretch raises intracellular Ca (Ca) in many cell types. Luminal flow-derived stretch stimulates O production by thick ascending limbs (THALs). Renal O is greater in Dahl salt-sensitive (SS) than salt-resistant (SR) rats.

Effects of reactive oxygen species on renal tubular transport.

Reactive oxygen species (ROS) play a critical role in regulating nephron transport both via transcellular and paracellular pathways under physiological and pathological circumstances. Here, we review the progress made in the past ~10 yr in understanding how ROS regulate solute and water transport in individual nephron segments. Our knowledge in this field is still rudimentary, with basic information lacking.

Fructose reabsorption by rat proximal tubules: role of Na-linked cotransporters and the effect of dietary fructose.

Fructose consumption has increased because of widespread use of high-fructose corn syrup by the food industry. Renal proximal tubules are thought to reabsorb fructose. However, fructose reabsorption (J) by proximal tubules has not yet been directly demonstrated, nor the effects of dietary fructose on J.

Dietary Fructose Increases the Sensitivity of Proximal Tubules to Angiotensin II in Rats Fed High-Salt Diets.

Dietary fructose causes salt-sensitive hypertension. Proximal tubules (PTs) reabsorb 70% of the filtered NaCl. Angiotensin II (Ang II), atrial natriuretic peptide (ANP) and norepinephrine (NE) regulate this process.

Incidence and characteristics of the nocebo response from meta-analyses of the placebo arms of clinical trials of olanzapine for bipolar disorder.

Objectives: In the clinical setting, the nocebo phenomenon is where clinical worsening or adverse events occur as a response to a treatment, in a situation in which conditioning from previous treatment exposure and/or expectations of sickness or symptoms lead to sickness and symptoms in a conditioned or expectant individual. The nocebo response may thus be a confounder in clinical treatment and clinical research. There is a need to know how to predict if an individual is likely to be a nocebo responder, and how significant and commonplace the nocebo effect might be.

Rats with ventral hippocampal damage are impaired at various forms of learning including conditioned inhibition, spatial navigation, and discriminative fear conditioning to similar contexts.

The ventral hippocampus (vHPC) has been implicated in learning and memory functions that seem to differ from its dorsal counterpart. The goal of this series of experiments was to provide further insight into the functional contributions of the vHPC. Our previous work implicated the vHPC in spatial learning, inhibitory learning, and fear conditioning to context.

NADPH oxidase 4-derived superoxide mediates flow-stimulated NKCC2 activity in thick ascending limbs.

Luminal flow augments Na reabsorption in the thick ascending limb more than can be explained by increased ion delivery. This segment reabsorbs 30% of the filtered load of Na, playing a key role in its homeostasis. Whether flow elevations enhance Na-K-2Cl cotransporter (NKCC2) activity and the second messenger involved are unknown.

The effects of pool shape manipulations on rat spatial memory acquired in the Morris water maze.

The Morris water maze is a popular task for examining spatial navigation and memory in rats. Historically, emphasis has been put on extramaze cues as the primary environmental feature guiding navigation and spatial memory formation. However, other features of the environment may also be involved.

A Rare Case of Infantile Myofibromatosis Presenting to the Emergency Department as Undiagnosed Long Bone Fractures.

Infantile myofibromatosis is a disorder of mesenchymal tumors that usually presents within the first 2 years of life. Most patients initially present because of the presence of visible or palpable subcutaneous tumors. We report a case of a fussy 5-week-old infant who presented to an emergency department with bilateral femur fractures initially thought to be due to nonaccidental trauma or a metabolic bone disorder.

Dietary Fructose Enhances the Ability of Low Concentrations of Angiotensin II to Stimulate Proximal Tubule Na⁺ Reabsorption.

Fructose-enriched diets cause salt-sensitive hypertension. Proximal tubules (PTs) reabsorb 70% of the water and salt filtered through the glomerulus. Angiotensin II (Ang II) regulates this process.

Evidence of a role for orbital prefrontal cortex in preventing over-generalization to moderate predictors of biologically significant events.

The mammalian brain is specialized to acquire information about environmental predictors of biologically significant events. However, environments contain an array of stimuli from which animals must ascertain which ones are meaningful in the current situation. This kind of uncertainty is inherent in the discriminative fear conditioning to context task (DFCTC) during which rats are trained to associate one context with foot-shock and another distinct context with no event.

Luminal flow induces NADPH oxidase 4 translocation to the nuclei of thick ascending limbs.

Superoxide (O2 (-)) exerts its physiological actions in part by causing changes in gene transcription. In thick ascending limbs flow-induced O2 (-)production is mediated byNADPHoxidase 4 (Nox4) and is dependent on protein kinase C (PKC). Polymerase delta interacting protein 2 (Poldip2) increases Nox4 activity, but it is not known whether Nox4 translocates to the nucleus and whether Poldip2 participates in this process.

Angiotensin II stimulates superoxide production by nitric oxide synthase in thick ascending limbs.

Angiotensin II (Ang II) causes nitric oxide synthase (NOS) to become a source of superoxide (O2 (-)) via a protein kinase C (PKC)-dependent process in endothelial cells. Ang II stimulates both NO and O2 (-) production in thick ascending limbs. We hypothesized that Ang II causes O2 (-) production by NOS in thick ascending limbs via a PKC-dependent mechanism.

Barriers to developing a valid rodent model of Alzheimer's disease: from behavioral analysis to etiological mechanisms.

Sporadic Alzheimer's disease (AD) is the most prevalent form of age-related dementia. As such, great effort has been put forth to investigate the etiology, progression, and underlying mechanisms of the disease. Countless studies have been conducted, however, the details of this disease remain largely unknown.

Maintained directional navigation across environments in the Morris water task is dependent on vestibular cues.

An experiment was designed to test the hypothesis that an internally generated sense of spatial orientation contributes to navigation by rats in the Morris water task and to determine whether this strategy is dependent on vestibular cues. Rats were trained in a standard hidden platform procedure in which they received 8 daily swim trials. In a probe test, rats were carried in an opaque box to a pool located in a novel adjacent environment.

Endogenous flow-induced nitric oxide reduces superoxide-stimulated Na/H exchange activity via PKG in thick ascending limbs.

Luminal flow stimulates endogenous nitric oxide (NO) and superoxide (O2 (-)) production by renal thick ascending limbs (TALs). The delicate balance between these two factors regulates Na transport in TALs; NO enhances natriuresis, whereas O2 (-) augments Na absorption. Endogenous, flow-stimulated O2 (-) enhances Na/H exchange (NHE).